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A wind-tunnel model support correction estimates the aerodynamic contribution of a model's mounting system to measured forces and torques. It can include the support's direct load and the altered fluid flow produced when support and model are together. An empty-tunnel support tare addresses the first effect but need not identify the second.

For a single load channel, write the defined measurement model asHere $F_M$ is the desired isolated-model load, $F_S$ is the support-only load and $I_{MS}$ is the wind-tunnel support interaction residual. The equations assume the same channel zero, conditions and support configuration, with other loads already removed. For stipulated values $F_M=20\mathrm{N}$, $F_S=3\mathrm{N}$ and $I_{MS}=2\mathrm{N}$, simple tare subtraction reports $22\mathrm{N}$, retaining a 10% bias relative to the desired load.

This limitation affected real design data. In their 1939 report, Eastman N. Jacobs and Ira H. Abbott found that support interference had made published airfoil drag coefficients too large and had exaggerated their increase with section thickness. Their correction therefore changed more than a single constant offset: it affected the inferred trend used to compare airfoil shapes.^[ref]

A proposed diagnostic repeats measurements with altered supports or attachment positions while maintaining a common target condition. Dependence on the mounting arrangement demonstrates a setup sensitivity; extrapolating to an unmounted model requires a justified mathematical model, not merely averaging the mounts. Wind-off orientation tares, support-only wind-on loads and model–support interactions answer different questions. Record each separately and propagate its measurement uncertainty through the reported correction.